Wembley National Stadium Limited have less than two weeks to avoid further embarrassment by convincing the NFL that the venue will be ready in time to stage the first ever regular season fixture to be held outside of North America.

London was yesterday unveiled as the chosen city for the event but, amid reports that Wembley had fought off competition from Twickenham to host it, the NFL insisted that both stadiums had yet to prove their "readiness". American football's governing body aims to announce its choice before Super Bowl XLI, which takes place on Sunday, February 4, in Miami.

"Both venues have undergone significant construction work recently and it is important to us that we understand the state of readiness of both stadiums," said Mark Waller, senior vice-president of NFL international. "We're looking primarily at the infrastructure and the facilities of the two venues and how they can accommodate not just the game itself but also the supporting requirements, training facilities and accommodation. Moving two teams over from the US for a regular season game is an incredibly tough logistical challenge so that's also a primary focus."

Fortunately for WNSL, who are confident this season's FA Cup final in May will mark the opening of new Wembley, the NFL commissioner, Roger Goodell, expects the game to be played between late September and mid-October, but an exact date is yet to be finalised. That will come as a relief to the stadium operator. "We are in discussions with the NFL about possibly staging the event at Wembley and we are very hopeful the event will be played here," said a WNSL representative.

However, the NFL will be sure to discuss Wembley's availability with caution. The 2006 FA Cup final was supposed to be the £750m, 90,000-capacity stadium's first event but the developers Multiplex failed to deliver on time and a series of humiliating setbacks has ensued. Four music concerts, as many domestic and international football matches and the 2006 rugby league Challenge Cup final had to be cancelled last year.

Goodell also insisted that the competing teams had not yet been agreed, despite speculation linking the Miami Dolphins with a "home" tie against the New York Giants. That decision is expected to be confirmed, along with the venue, on Friday February 2.

"The first priority is that we select two teams that generate the most enthusiasm for our fans in London and the UK," explained Goodell. "It's been extraordinary to see the kind of reaction we've had from the clubs and the cities wanting to have their clubs represented. We are confident we will have two very popular and outstanding football teams to represent the NFL."